If the value went up to the point you have 20% or more, then you might be able to just get an appraisal, but definitely get out of the PMI.
My cousin did this to ditch his 2nd mortgage (got the second to avoid PMI, but then had 2 payments, one with a higher rate). After 4 years, the value went from something like $100,000 to $125,000, so he re-financed and got a new primary mortgage, which paid off the 2nd mortgage.